I know this is an older thread, but wanted to know if anyone knew about the whelks that were not harmful? I have a ton of snails that are tiny littl eguys with a snorkle like appendage that cruise the sand, and then I have a ton of bigger 1/2' guys that have the same snorkle that bury themselves in the sand and climb the walls a little. I am afraid of predatory whelks, but do not want to loose the sand shifting that they offer. Any help on what I can do is greatly appreciated.